This invention relates to powered positionable chairs in which a top section supported by a base is moved in an arcuate path relative to the base. A problem of paramount importance with positionable chairs that provide arcuate seat movement is that the power assembly components and the seat and base must be so structured that they will not interfere with one another during operation. The sections must be strongly based with transverse bracing, and yet must provide clearance for movements of the power drive mechanism. This problem is particularly acute in a positionable chair that provides arcuate movement, as distinguished from one which provides only linear movement of the seat relative to the base, as the power drive parts are more or less chordal to the arc of movement.
Powered positionable chairs that have arcuate seat-base movement are known in the prior art. For example, in Ferro U.S. Pat. No. 3,232,575, there is disclosed a positionable chair in which a seat is moved in an arcuate path relative to the base. In such prior art chairs that rely on a pulley belt system, there has existed a problem of maintaining alignment of the pulley belt, especially when the pulleys are tilted relative to one another during chair operation. Also such pulley arrangements can add to the complexity of a power mechanism.
Prior art devices have had a tendency to move themselves out of alignment during chair operation, and there has been a need to have a mounting system which can guide the operation of the power assembly so that alignment of the power assembly with the seat and base is maintained.
Problems have also existed in the prior art with the length of time expended in detaching a power assembly from a chair so that maintenance on the assembly can be performed on location without obstruction from the chair parts. Such detachment also eliminates the necessity of removing the entire chair to a repair shop should it be necessary to take the power assembly to the repair shop. There has been a desire to reduce the complexity of the mounting for power assemblies so that detachment of the power assembly can be performed easily.
Problems have also existed in the prior art with the length of time expended in detaching a power assembly from a chair so that maintenance on the assembly can be performed on location without obstruction from the chair parts. Such detachment also eliminates the necessity of removing the entire chair to a repair shop should it be necessary to take the power assembly to the repair shop. There has been a desire to reduce the complexity of the mounting for power assemblies so that detachment of the power assembly can be performed easily.
Complexity of prior arcuate movement power assemblies has also made handling of the assemblies awkward and there has been a need for a power assembly that can be handled easily in positioning it in an arcuate movement chair.
In the prior art, as arcuate movement of the seat occurs, exposed power assembly parts can move into chair clothing and upholstery and it has been desired to conceal moving assembly parts to avoid such contact.